Ideal root temperature

[Goodbloke]

8 hours ago, yan said:

What effect on stretch have you found? Is it possible to reduce it by controlling the temperature difference from lights on to off?

I picked up the idea on here, I've done zero research into the what's & why's. I've not run clones side by side with the temps being the only difference. 

I initially ran a seed trying to maintain 28 constantly through 18/6 & first 3 weeks of 12/12. Second run, aimed for an increased temperature lights off, plant didn't seem to enjoy the experience & looked a bit 'off' 

I noticed a difference, but, particularly as I was expecting a difference....... 

Don't think it's just in my head. 

I'd need a bloody good reason to move away from a more 'traditional' method though as I found it a pain to try and auto control the environment & at times couldn't maintain conditions particularly with the lights off increase.

There is a name for this method, goes by an acronym. Can't remember what. 

[latigid aikon]

47 minutes ago, Military Grade said:

Because if the probe is at the bottom the rest of the upper pot doesn't get to temperature, that's why it's recommended to have it ⅔ down and set it to 24c, this way the bottom of the pots sits at around 26c the middle at 24c and the top of the pot 22c, this is more optimal

Have you actually measured that because it's not what I found when I did. Heat rises and is conducted through damp media surprisingly well.

[Axiom]

@latigid aikon He's right ... it will obviously be warmest at the source of the heat which is at the bottom. The top will be coldest because the heat is being lost from the open top, cooling it off. 
I still have my probe at the bottom though because when growing in a cold room, you want the max temp possible at the roots within limits. That way you get max power... like the old car magazines with the tits in them...  

[Military Grade]

Just now, latigid aikon said:

Have you actually measured that because it's not what I found when I did. Heat rises and is conducted through damp media surprisingly well.

Yeah, I used my glass soil thermometer pen when I first got it and the heat mat thermostat set, was on fabric pots at the time so I cut a hole in three different places and took measurements from all three long after the heat mat and probe had reached the target temperature.

[Goodbloke]

Shit, @AxiomI think you're right. I'm getting muddled up with my humidity inkbird, that's the wifi unit. 

[latigid aikon]

@Military GradeI used Inkbird probes at the base and about half way up when I tested it and like I say that's not what I found... Maybe fabric pots lose heat more easily?

Just now, Axiom said:

He's right ... it will obviously be warmest at the source of the heat which is at the bottom. The top will be coldest because the heat is being lost from the open top, cooling it off. 

Have you actually measured it or is that theoretical?

Just now, Axiom said:

when growing in a cold room,

I have a warm room with two tube heaters, the air temperature is higher than the temperature I heat the soil to so the pots aren't really losing heat at the top where the air is warmer.

[Axiom]

@latigid aikon I measure it once every couple weeks and when the seasons change.
The base is 30c at the moment and the top is around 21c. 

Yeah my air intake is pretty cold so might be different for you  

[latigid aikon]

@Axiom Haha yes that could explain it. To be clear I run the Inkbird controlling my tube heaters at 29ºc lights on and 26ºc lights off while the root heater is at 26ºc and 23ºc respectively. Are you growing with LEDs and 21ºc air temps?

[Axiom]

Just now, latigid aikon said:

@Axiom Are you growing with LEDs and 21ºc air temps?

 

Exactly. In a cold unheated building. 

 

[latigid aikon]

@Axiom I used my loft for over a decade in those sort of temperatures but with HPS, I didn't think LED would work at 21ºc?!

 

I think we should probably conclude that everyone should measure their soil temps at several levels initially because it's likely to vary according to environment and possibly type of pot?

[Axiom]

@latigid aikon I'm hovering around 23c most days and around 18.5c lights off. I didn't think the LED thing would work either.

I'm not even running the oil heater during lights on... I do have 2 side by side. So that's 2 heat mats and 2 lights. Passive intake.

[Military Grade]

31 minutes ago, latigid aikon said:

@Axiom I used my loft for over a decade in those sort of temperatures but with HPS, I didn't think LED would work at 21ºc?!

 

I think we should probably conclude that everyone should measure their soil temps at several levels initially because it's likely to vary according to environment and possibly type of pot?

Maybe also how much perlite and how compressed the soil has/is.

[lennyd79]

Mine are 21c which I feel is warm enough but not warm enough for fungi to thrive.